The MCP3421 ADC can be used for various high accuracy analog-to-digital data conversion applications where ease of use, low power consumption and small footprint are major considerations.The MCP3421 is a single channel low-noise, high accuracy delta-sigma A/D converter with differential inputs and up to 18 bits of resolution in a small SOT-23-6 package.

The on-board precision 2.048V reference voltage enables a differential input range of ±2.048V. The device uses a two-wire I2C™ compatible interface and operates from a single power supply ranging from 2.7V to 5.5V. The MCP3421 ADC performs conversions at rates of 3.75, 15, 60 or 240 samples per second with corresponding resolutions of 18, 16, 14 and 12 bits. The onboard programmable gain amplifier (PGA) provides gain up to 8x. The device has two conversion modes: Continuous mode and One-Shot mode. In One-Shot mode, the device enters a low current standby mode automatically after a conversion, greatly reducing power use.

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In this example we will connect a MMA8452Q accelerometer to an Arduino Uno

Lets look at some information about the sensor

The MMA8452Q is a smart, low-power, three-axis, capacitive, micromachined accelerometer with 12 bits of resolution. This accelerometer is packed with embedded functions with flexible user programmable options, configurable to two interrupt pins. Embedded interrupt functions allow for overall power savings relieving the host processor from continuously polling data.

The MMA8452Q has user selectable full scales of ±2 g/±4 g/±8 g with high-pass filtered data as well as non-filtered data available real-time. The device can be configured to generate inertial wakeup interrupt signals from any combination of the configurable embedded functions allowing the MMA8452Q to monitor events and remain in a low-power mode during periods of inactivity

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The ADS1115 device is a precision, low-power, 16-bit, I2C-compatible, analog-to-digital converters (ADCs) offered in an ultra-small, leadless, X2QFN-10 package, and a VSSOP-10 package. The device incorporates a low-drift voltage reference and an oscillator. The converter also incorporates a programmable gain amplifier and a digital comparator. These features, along with a wide operating supply range, make the converter well suited for power- and space-constrained, sensor measurement applications.

The ADS1115 perform conversions at data rates up to 860 samples per second (SPS). The PGA offers input ranges from ±256 mV to ±6.144 V, allowing precise large- and small-signal measurements. The converter features an input multiplexer that allows two differential or four single-ended input measurements. Use the digital comparator in the ADS1115 for under- and overvoltage detection.

The ADS1115 operates in either continuous-conversion mode or single-shot mode. The devices are automatically powered down after one conversion in single-shot mode; therefore, power consumption is significantly reduced during idle periods.

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In this video we compile and program the Arduino and show you the output. We also show a layout and schematic in fritzing, we tied the A0 to A3 to various voltages, at the end we removed these so the input is ‘floating’

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In this example we will connect a CCS811 gas sensor to an arduino, lets look at the sensor

CCS811 is a low-power digital gas sensor solution, which integrates a gas sensor solution for detecting low levels of VOCs typically found indoors, with a microcontroller unit (MCU) and an Analog-to-Digital converter to monitor the local environment and provide an indication of the indoor air quality via an equivalent CO2 or TVOC output over a standard I2C digital interface.